1. Field of the Technology
The present invention relates to the field of communications, and more particularly to a method for bearer control, bearer deletion, data distribution, and multicast broadcast service modification.
2. Background of the Invention
IEEE802.16 is issued by the Institute of Electrical and Electronics Engineers (IEEE) in December of 2001 for providing standards of last mile wireless broadband access in a metropolitan area network (MAN).
Meanwhile, numerous equipment and component providers set up the Worldwide Interoperability for Microwave Access (WiMAX) forum organization aimed at accelerating the deployment of a broadband wireless network based on the above IEEE802.16 series standards by ensuring the compatibility and interoperability between broadband wireless access equipments. Therefore, in common cases, a system for realizing the wireless broadband access based on the IEEE802.16 series standards is called a WiMAX system.
FIG. 1 shows a WiMAX end-to-end reference model. As shown in the figure, the WiMAX mainly includes a mobile station (MS)/subscriber station (SS), an access service network (ASN), and a connectivity service network (CSN).
The ASN is defined as a network function collection for providing a wireless access service to a WiMAX user terminal, and includes network elements of a base station (BS) and an ASN gateway (ASN-GW). One ASN may be shared by multiple CSNs.
The main functions of the ASN include functions of the BS and the ASN-GW. The functions of the BS include provision of an L2 connection between the BS and the SS/MS, wireless resource management, measurement and power control, and compression and encryption of air interface data. The functions of the ASN-GW include provision of a proxy function for authentication, authorization, and accounting functions of the SS/MS, support of the network discovery and selection of an NSP, and provision of a relay function, for example, IP address allocation of L3 information for the SS.
The CSN is defined to provide an IP connection service to the WiMAX user terminal. The functions of the CSN mainly include: IP address allocation of the SS/MS, Internet access, functioning as an authentication, authorization, and accounting (AAA) proxy or server, user-based authorization control, tunnel from the ASN to the CSN, accounting of a WiMAX user and settlement between operators, tunnel between CSNs in roaming cases, handover between ASNs, and various WiMAX services (for example, location-based services, multimedia multicast and broadcast services, and IP multimedia subsystem services).
The MS/SS is a (mobile) user equipment with which the user accesses a WiMAX network.
The WiMAX network wireless side is a wireless MAN access technique based on the IEEE 802.16d/e standards and nowadays mainly conforms to the IEEE 802.16-2004 (802.16d) standard formulated in July of 2004. The working frequency band of the IEEE 802.16-2004 (802.16d) standard is from 2 GHz to 11 GHz, and is a mixed frequency band of authorization and non-authorization. Orthogonal frequency division multiplexing (OFDM) and orthogonal frequency multiple access (OFDMA) physical layers are employed to effectively resist multipath fading. In the case of a most preferred channel fading, the transmission rate approaches to 75 Mbps. The IEEE 802.16-2004 (802.16d) standard is used in the non-line-of-sight point-to-multipoint technology in the MAN, and is mainly in the forms of fixed and nomadic networks. Technologies supporting simple mobile communication and full mobile communication have been added to the IEEE 802.16e under discussion.
With the rapid development of Internet, the point-to-point communication can no longer satisfy people's demand for mobile communications. As a result, a great many multimedia services spring up. Among them, some application services, for example, video on demand (VOD), television broadcasting, video conference, online education, and interactive games, require multiple users to receive the same data at the same time. Compared with general data, these mobile multimedia services are mainly characterized by large amount of data, long duration, and sensitivity to time delay. The current IP multicast technology is only applicable to a wired IP network instead of a mobile network, because the mobile network has specific network structures, functional entities, and wireless interfaces which are all different from those of the wired IP network.
In order to effectively utilize mobile network resources, a multicast broadcast service (MBS) is introduced into the WiMAX, i.e., a point-to-multipoint service in which one data source sends data to multiple users is provided in a mobile network so as to share the network resources and improve the utilization of the network resources, especially air interface resources. The MBS introduced into the WiMAX enables not only multicast and broadcast of plain text, low-rate messages, but also multicast and broadcast of high-speed multimedia services, which no doubt conforms to the trend of development of mobile data in the future.
The MBS based on the WiMAX network supports two access modes: single-BS access and multi-BS access. In the multi-BS access mode, all BSs in one MBS zone (identified by an MBS_zone ID) use the same multicast connection ID (MCID) and MBS group security association (MBS GSA) to send contents of the same MBS flow, and a terminal that has registered an MBS service can receive the MBS contents via multiple BSs in the MBS zone. Moreover, when moving across the BSs in the MBS zone, the terminal in an idle mode receives the MBS without being affected when connection reestablishment is not needed, thereby realizing a seamless handover of the MBS.
Some globally defined service flows may carry broadcast or multicast information of multiple SSs/MSs. These service flows have quality of service (QoS) parameters and may further need to be encrypted by a globally defined data encryption key. In the WiMAX network, a service flow identifier (SFID) is adopted to identify a unidirectional service flow and a connection ID (CID) is adopted to identify a connection. All service flows are transmitted through a media access control (MAC) layer connection at an air interface, i.e., the SFID needs to be mapped to a CID. The MCID is a CID dedicated for multicast connection. Meanwhile, the 802.16e stipulates the use of an MBS contents ID to identify a multicast service. A protocol data unit (PDU) transmitted on one MCID includes one or more MBSs.
In order to use a macro diversity to improve the reception performance, an MBS mapping (MBS-MAP) message is introduced into the IEEE802.16. The message is transmitted in an MBS zone for notifying the physical channel resource allocated to a specific multicast CID in a given MBS zone. The MBS-MAP message adopts an MBS_DATA_IE to further designate a modulation and coding mode (DIUC) and power offset (boosting) used by various service data blocks on a designated physical channel resource (Burst) and locations of the next MBS service frame and the next MBS-MAP message frame. Therefore, as long as the MBS-MAP message is detected correctly, the terminal can obtain the physical channel resource corresponding to the multicast connection expected to be received according to the message, get the modulation and coding mode, power offset, etc., used on the physical channel resource, and further determine the location of the MBS frame including the multicast connection in the next frame, so as to normally receive data through multicast connection.
An air interface link layer connection ID may be a CID or an MCID. One air interface link layer connection may bear one or more upper layer data flows. The standard defines the use of a contents ID to distinguish different upper layer data flows borne by the air interface link layer connection. When one air interface link layer connection bears multiple contents, a logical channel ID (LCID) is used at the link layer to identify the contents, so as to indicate what contents the current link layer packet bears. The LCID and the MCID uniquely correspond to one contents ID.
One MBS zone is managed by one MBS proxy. The MBS proxy maintains MCID resources and may be located on an ASN GW, an MBS server, or an independent functional entity.
However, specific schemes on how to establish and remove a bearer at the start or end of an MBS session have not been yet provided. When an MBS service at the network side changes, resources (including the establishment of a tunnel) reserved for the MBS service cannot be modified, either, which affects the realization of the MBS service and even interrupts the MBS service to cause a waste of resources.